CFM (`cfm`)

Layer: L2 (data link)
Header: variable length
Notes: PTP / ESMC / CFM / R-APS / 802.3ah OAM (P2)

Reached from

Lower layer	Selector	Value
`ethernet2`	`ethertype`	35074 (0x8902)
`dot1q`	`ethertype`	35074 (0x8902)
`dot1ad`	`ethertype`	35074 (0x8902)

Fields

Field	Type	Default	Auto	Description
`md_level`	`uint(3)`	`0`		Maintenance domain / MEG level (0-7).
`version`	`uint(5)`	`0`		CFM version (0; 1 for R-APS of G.8032v2).
`opcode`	`enum(8)`	`3` (lbm)		OpCode: 1 CCM, 2 LBR, 3 LBM, 4 LTR, 5 LTM, 33 AIS, 35 LCK, 37 TST, 39 Linear APS, 40 R-APS, 41 MCC, 42 LMR, 43 LMM, 45 1DM, 46 DMR, 47 DMM, 52 CSF, 53 1SL, 54 SLR, 55 SLM …
`flags`	`uint(8)`	`0`		Flags (OpCode specific).
`first_tlv_offset`	`uint(8)`	`4`		Offset of the first TLV from the end of this field (constant for each OpCode).
`data`	`bytes` — rest of the PDU	`00 00 00 01 00`		Rest of the PDU after the first TLV offset, as octets (OpCode specific fields and TLVs).

`opcode`

Value	Name
1 (0x01)	`ccm`
2 (0x02)	`lbr`
3 (0x03)	`lbm`
4 (0x04)	`ltr`
5 (0x05)	`ltm`
33 (0x21)	`ais`
35 (0x23)	`lck`
37 (0x25)	`tst`
39 (0x27)	`linear_aps`
40 (0x28)	`ring_aps`
41 (0x29)	`mcc`
42 (0x2a)	`lmr`
43 (0x2b)	`lmm`
45 (0x2d)	`one_dm`
46 (0x2e)	`dmr`
47 (0x2f)	`dmm`
48 (0x30)	`exr`
49 (0x31)	`exm`
50 (0x32)	`vsr`
51 (0x33)	`vsm`
52 (0x34)	`csf`
53 (0x35)	`one_sl`
54 (0x36)	`slr`
55 (0x37)	`slm`

Next layer

The next layer is selected by opcode; when the field is Auto the builder writes the value of the protocol stacked above.

Value	Protocol	Note
1 (0x01)	`cfm_ccm`	re-decodes this layer
2 (0x02)	`cfm_lbr`	re-decodes this layer
3 (0x03)	`cfm_lbm`	re-decodes this layer
4 (0x04)	`cfm_ltr`	re-decodes this layer
5 (0x05)	`cfm_ltm`	re-decodes this layer
33 (0x21)	`cfm_ais`	re-decodes this layer
35 (0x23)	`cfm_lck`	re-decodes this layer
37 (0x25)	`cfm_tst`	re-decodes this layer
40 (0x28)	`cfm_raps`	re-decodes this layer
42 (0x2a)	`cfm_lmr`	re-decodes this layer
43 (0x2b)	`cfm_lmm`	re-decodes this layer
45 (0x2d)	`cfm_1dm`	re-decodes this layer
46 (0x2e)	`cfm_dmr`	re-decodes this layer
47 (0x2f)	`cfm_dmm`	re-decodes this layer
52 (0x34)	`cfm_csf`	re-decodes this layer
53 (0x35)	`cfm_1sl`	re-decodes this layer
54 (0x36)	`cfm_slr`	re-decodes this layer
55 (0x37)	`cfm_slm`	re-decodes this layer

Sample templates

cfm-generic — templates/protocols/oam/cfm-generic.wpg.yaml